Antimicrobial phase-separating glass and glass ceramic articles and laminates

ABSTRACT

A glass laminate for an architectural element has a glass substrate coupled to the architectural element and defines a primary surface facing away from the architectural element. A phase-separable glass cladding is coupled to the primary surface. The cladding has an interconnected matrix with a first phase composition and a second phase that has a second phase composition different than the first phase composition. The second phase is distributed throughout the interconnected matrix. A copper phase is distributed within the interconnected matrix. The glass cladding has an antimicrobial log kill rate greater than about 4 as measured by an EPA Copper Test Protocol.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.15/202,272 filed on 5 Jul. 2016, which claims the benefit of priorityunder 35 U.S.C. § 119 of U.S. Provisional Application Ser. No.62/189,880 filed on 8 Jul. 2015, the contents of both of which arerelied upon and incorporated herein by reference in their entireties.

TECHNICAL FIELD

The present disclosure generally relates to antimicrobial articles.Embodiments described herein relate to copper-containing articlesincluding glass and/or glass-ceramic having improved antimicrobialbehavior, as well as to methods of making and using the articles.

BACKGROUND

Architectural elements utilizing glass, such as countertops and displayfeatures, have become increasingly more prevalent. Often, surfacesdefined by these elements are touched and handled by people and aretherefore susceptible to carrying and transmitting disease.

To minimize the presence of microbes on these surfaces, so-called“antimicrobial” properties have been imparted to a variety of glass andglass-ceramic articles. Such articles can exhibit poor antimicrobialefficacy under ordinary use conditions despite performing adequatelyunder generally-accepted or standardized testing conditions and/or canbe costly to manufacture (e.g., when expensive metals or alloys are usedas the antimicrobial agent or when additional steps are required tointroduce the antimicrobial agent into or onto the surface). Thesedeficiencies ultimately can make it impractical to implement theantimicrobial articles.

The biological activity of copper is due in a large part to its abilityto exist in what is termed a “free” state as metallic copper or an“ionic” state as a copper salt or oxide. While copper is almost alwayscombined with other elements or minerals, under certain conditions,copper can exist in the ionic or free copper state, both of which arebiologically active and thus give copper the ability to kill bacteria,viruses and fungi.

While there has been some discussion in the literature of usingelemental copper and copper ions as antimicrobial agents, most of it hasbeen generalized and not applicable to modern product forms. There hasnot been a description of the specific nature of how particular copperspecies and forms (e.g., copper nanoparticles) can be employed to obtainand optimize antimicrobial efficacy without detriment to otherproperties and capabilities of the product.

There accordingly remains a need for technologies that providecopper-containing glass, glass-ceramics or other types of articles withimproved antimicrobial efficacy under both ordinary use andgenerally-accepted testing conditions. It would be particularlyadvantageous if such technologies did not adversely affect otherdesirable properties of the articles, such as optical or aestheticproperties. It would also be advantageous if such technologies could beproduced in a relatively low-cost manner. It is to the provision of suchtechnologies that the present disclosure is directed.

SUMMARY

According to one aspect of this disclosure, phase-separable glassincluding an interconnected matrix with a first phase composition and asecond phase that has a second phase composition different than thefirst phase composition. The second phase is distributed throughout theinterconnected matrix. A copper phase is distributed within theinterconnected matrix. The glass has an antimicrobial log kill rategreater than about 4 as measured by an EPA Copper Test Protocol. In oneor more embodiments, the phase separable glass may be utilized in aglass laminate for an architectural element, which may include a glasssubstrate coupled to the architectural element and defines a primarysurface facing away from the architectural element. The phase-separableglass may form a cladding that is coupled to the primary surface.

According to another aspect of this disclosure, a glass article has abulk concentration of copper between about 1.0 mol. % and about 20.0mol. %. The glass article also has an interconnected matrix and a secondphase distributed throughout the interconnected matrix. The second phasehas a copper concentration less than about 0.5 mol. %. A copper phase isdistributed within the interconnected matrix. The copper phase comprisesa plurality of copper structures that have a largest cross-sectionaldimension greater than about 0.1 microns.

According to yet another aspect of this disclosure, a method of creatingan antimicrobial glass article that includes the steps of providing aphase-separable glass article with a bulk copper concentration betweenabout 1.0 mol. % and about 20 mol. %, heat treating the article to forman interconnected matrix that has at least one second phase disposedthroughout the matrix, and precipitating a copper phase within thematrix and apart from the second phase. The second phase has less thanabout 1.0 mol. % copper.

Additional features and advantages will be set forth in the detaileddescription which follows, and, in part, will be readily apparent tothose skilled in the art from that description or recognized bypracticing the embodiments as described herein, including the detaileddescription which follows, the claims, as well as the appended drawings.

It is to be understood that both the foregoing general description andthe following detailed description are merely exemplary, and areintended to provide an overview or framework to understanding the natureand character of the claims. The accompanying drawings are included toprovide a further understanding, and are incorporated in and constitutea part of this specification. The drawings illustrate one or moreembodiments, and together with the description serve to explainprinciples and operation of the various embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a side view of a monolithic antimicrobial article accordingto one aspect of the disclosure;

FIG. 1B is a perspective view of a laminate antimicrobial articleaccording to another aspect of the disclosure;

FIG. 10 is a perspective view of an antimicrobial table according to oneaspect of the disclosure;

FIG. 1D is a perspective view of an antimicrobial countertop accordingto another aspect of the disclosure;

FIG. 2 is a schematic scanning electron microscope (SEM) micrograph inbackscatter mode of the article of FIG. 1A taken at area II of FIG. 1A;

FIG. 3A is an SEM micrograph of the glass article according to oneembodiment;

FIG. 3B is an SEM micrograph of the glass article according to anotherembodiment;

FIG. 3C is an SEM micrograph of the glass article according to yetanother embodiment; and

FIG. 4 is a bar chart depicting antimicrobial efficacy of theantimicrobial structures depicted in FIGS. 3A-C under the EPA CopperTest Protocol according to an aspect of the disclosure.

DETAILED DESCRIPTION

Referring now to the figures, wherein like reference numerals representlike parts throughout the several views, exemplary embodiments will bedescribed in detail. Throughout this description, various components maybe identified having specific values or parameters. These items,however, are provided as being exemplary of the present disclosure.Indeed, the exemplary embodiments do not limit the various aspects andconcepts, as many comparable parameters, sizes, ranges, and/or valuesmay be implemented. Similarly, the terms “first,” “second,” “primary,”“secondary,” “top,” “bottom,” “distal,” “proximal,” and the like, do notdenote any order, quantity, or importance, but rather are used todistinguish one element from another. Further, the terms “a,” “an,” and“do not denote a limitation of quantity, but rather denote the presenceof “at least one” of the referenced item.

As used herein, the term “antimicrobial” means an agent or material, ora surface containing the agent or material, that will kill or inhibitthe growth of microbes from at least two families consisting ofbacteria, viruses and fungi. The term as used herein does not mean itwill kill or inhibit the growth of all species of microbes within suchfamilies, but that it will kill or inhibit the growth of one or morespecies of microbes from such families. When an agent is described as“antibacterial,” “antiviral” or “antifungal,” it means that the agentwill kill or inhibit the growth of only bacteria, viruses or fungi,respectively.

As used herein, the term “Log Reduction,” “log kill” or “LR” means−log(C_(a)/C₀), where C_(a)=the colony form unit (CFU) number of theantimicrobial surface containing Cu nanoparticles and C_(o)=the colonyform unit (CFU) of the control glass surface that does not contain Cunanoparticles. That is, LR=−log(C_(a)/C_(o)). As an example, a log killof 3=99.9% of bacteria or virus killed and a log kill of 5=99.999% ofbacteria or virus killed.

Described herein are various antimicrobial articles that haveantimicrobial efficacy both under ordinary use conditions and undergenerally-accepted testing conditions, along with methods for theirmanufacture and use. The antimicrobial articles also have improvedantimicrobial efficacy both under ordinary use conditions and undergenerally-accepted testing conditions relative to similar ornearly-identical articles.

Referring now to the depicted embodiments of FIGS. 1A-D, anantimicrobial article 10 is schematically depicted. The antimicrobialarticle 10 may be a monolithic structure (FIG. 1A) or may at leastpartially comprise a laminate structure (FIG. 1B). In laminateembodiments, the antimicrobial article 10 may include a substrate 14 andat least one cladding layer. In the depicted embodiment of FIG. 1B, theantimicrobial article 10 includes a first cladding 18 and a secondcladding 22. The substrate 14 generally defines a first surface 26 and asecond surface 30 which is opposed to the first surface 26. The firstand second claddings 18, 22 may be fused, or otherwise bonded, to thefirst and second surfaces 26, 30 of the substrate 14, respectively. Itshould be understood that although the antimicrobial article 10 isdepicted as having two claddings in FIG. 1B, it may have only a singlecladding layer or more than two cladding layers without departing fromthe spirit of this disclosure.

The antimicrobial article 10 may be useful in a variety of applicationswhere a reduction in microbial growth is desirable. For example, theantimicrobial article 10 may be used as or in an architectural elementsuch as a table top 34 (FIG. 1 C), a countertop 38 (FIG. 1D), coasters,desk covers, patio furniture, and the like. Useful settings for thearchitectural elements may include healthcare settings (e.g., operatingrooms, patient examination rooms, corridors), private residences,offices, bathrooms, and high traffic environments. Additionalapplications of the antimicrobial article 10 include lightingapplications, light filtration applications, aesthetic displays designedto be touched, functional hardware (e.g., door handles, dishware), andsimilar applications. Additionally or alternatively, the antimicrobialarticle 10 may be utilized for building and automotive glazing. Theantimicrobial article 10 may be provided in particulate or fiber formand incorporated into various carriers (e.g., polymers, monomers,binders, solvents, and other materials) to form molded articles, formedarticles, coatings on substrates or other such articles.

In laminated embodiments of the antimicrobial article 10, the substratelayer 14 may be formed from a variety of materials including glasses,glass-ceramics, ceramics, polymers and metals. Exemplary glasscompositions include those capable of being fused or otherwise bonded(e.g., adhesively, chemically, mechanically) to the first and secondcladding layers 18, 22. In some embodiments, the substrate 14 mayinclude alkali metals and/or compounds containing alkali metals while,in other embodiments, the substrate 14 may be substantially free fromalkali metals and/or compounds containing alkali metals.

In one particular embodiment, the substrate 14 of the antimicrobialarticle 10 is formed from a glass composition which comprises from about60 to about 73 mol. % SiO₂; from about 5 to about 16 mol. % Al₂O₃, fromabout 0 to 16 mol. % B₂O₃; from about 0 to 16 mol. % Na₂O; from about 0to about 16 mol. % K₂O, wherein a total of Na₂O and K₂O is less than orequal to 16 mol. %; from about 0 to about 8 mol. % MgO; from about 0 toabout 16 mol. % CaO; from about 0 to about 16 mol. % SrO; from about 0to about 16 mol. % BaO; from about 0 to about 8 mol. % ZnO, wherein thesum of MgO+CaO+SrO+BaO+ZnO is from about 0 to about 20 mol. %. However,it should be understood that other glass compositions may be used toform the substrate 14 of the antimicrobial article 10, so long as thecomposition of the substrate 14 is capable of being fused or otherwisebonded to the glass composition of the first and second cladding layers18, 22.

A variety of processes may be used to form the laminated embodiments ofthe antimicrobial article 10 described herein including, withoutlimitation, a fusion lamination process, slot-draw lamination processes,and float glass processes. In one particular embodiment, theantimicrobial articles 10 may be formed by a fusion lamination processas described in U.S. Pat. No. 4,214,886, the salient portions of whichare incorporated herein by reference. In some embodiments describedherein, the glass compositions used for forming the first and secondcladding layers 18, 22 have a liquidus viscosity which renders themsuitable for use in a fusion draw process and, in particular, for use asa glass cladding composition in a fusion lamination process. Forexample, in some embodiments, the liquidus viscosity is greater than orequal to about 50 kPoise. In some other embodiments, the liquidusviscosity may be greater than or equal to 100 kPoise or even greaterthan or equal to 250 kPoise.

Referring now to FIG. 2, the antimicrobial article 10 may include aphase-separating glass. In monolithic embodiments of the antimicrobialarticle 10 (see FIG. 1A), the entire article 10 may be composed of aphase-separating glass, as depicted in FIG. 2. In embodiments where theantimicrobial article 10 is a laminated structure, the first and/orsecond cladding 18, 22 may include a phase-separating glass (see FIG.1B), as also depicted in FIG. 2. As shown in FIG. 2, thephase-separating glass (e.g., with antimicrobial article 10 in FIG. 1Aand 18, 22 claddings in FIG. 18) may include a spinodal phase-separatedglass which includes a first glass phase 50 and a second glass phase 54,each of the glass phases 50, 54 have different and distinctcompositions, and are separated within the article 10. It should beunderstood that certain implementations of the antimicrobial articlesdisclosed herein employ phase-separating glass with more than twophases. Phase-separation may occur upon exposure to a phase-separationtreatment, such as a heat treatment or the like. In some embodiments,the phase-separated glass includes an interconnected matrix 58 of glassformed from the first phase 50, with the second phase 54 dispersedthroughout the interconnected matrix 58 as discrete, unconnected regionsof glass having the composition of the second phase 54. The second phasemay itself be interconnected within the interconnected matrix of thefirst phase, be separate and discrete structures, or include bothdiscrete and continuous structures throughout the antimicrobial article10 or cladding 18, 22. In various embodiments, the durability, orcorrosion resistance of the first phase 50 and the second phase 54 towater, alkaline solutions, and/or acidic solutions may differ. Forexample, the first phase 50 may more readily dissolve in water and/oracidic solutions than the second phase 54 or vice versa.

In one embodiment, the antimicrobial article 10 and/or the first andsecond cladding layers 18, 22 may be formed from the glass compositiondisclosed in U.S. Patent Publication No. 20150037553, having a filingdate of Aug. 21, 2014 and entitled “Low CTE Alkali-FreeBoroaluminosilicate Glass Compositions and Glass Articles Comprising theSame,” the entirety of which is incorporated by reference herein. Inthis embodiment, the glass composition comprises a combination of SiO₂,Al₂O₃, B₂O₃, and alkaline earth oxides. Such a composition undergoesphase-separation upon heat treatment below the spinodal temperature.

In the foregoing exemplary phase-separating glass composition, SiO₂ isthe largest constituent and, as such, SiO₂ is the primary constituent ofthe glass network formed from the glass composition. In this embodiment,the glass composition generally includes SiO₂ in a concentration lessthan or equal to about 70 mol. % which may facilitate fusion-forming theglass composition. In some embodiments, the concentration of SiO₂ in theglass composition may range between about 50 mol. % and about 70 mol. %.In other embodiments, SiO₂ is present in the glass composition in aconcentration greater than or equal to about 55 mol. % and less than orequal to about 63 mol. %.

The phase-separating glass composition of this embodiment furtherincludes Al₂O₃. The concentration of Al₂O₃ in the glass composition isgenerally less than or equal to about 10 mol. % in order to facilitateformation of laminated embodiments of the antimicrobial article 10 usingfusion forming techniques. For example, in some embodiments, theconcentration of Al₂O₃ in the glass composition is greater than or equalto about 5 mol. % and less than or equal to about 10 mol. %. In some ofthese embodiments, the concentration of Al₂O₃ in the glass compositionmay be less than or equal to about 9 mol. %, less than or equal to about8 mol. %, less than or equal to about 7 mol. %, less than or equal toabout 6 mol. %, and less than or equal to about 5 mol. %.

The phase-separable glass composition of this embodiment may furtherinclude B₂O₃. The incorporation of B₂O₃ in the glass compositionfacilitates phase-separating the glass composition into a silica-richphase and a boron-rich phase. In some embodiments, the silica-rich phaseis substantially free of modifiers such as Ca, Sr, Mg and the like(e.g., such modifiers may be present in trace amounts or in amounts ofless than about 0.5 mol %, or less than about 0.1 mol %). In someinstances, the boron-rich phase may include one or more modifiers suchas Ca, Sr, Mg and the like. Where such modifiers are present in theboron-rich phase, they may be present in amounts greater than about 0.5mol % up to amounts described below with respect to the amount ofalkaline earth oxides present in the glass composition). In theseembodiments, the silica-rich phase may be more durable or corrosionresistant (i.e., less susceptible to dissolution in water and/or anacidic solution) than the boron-rich phase. B₂O₃ is generally present inthe glass composition in a concentration greater than or equal to about14 mol. %. For example, in some embodiments, B₂O₃ is present in theglass composition in a concentration greater than or equal to about 14mol. % and less than or equal to about 25 mol. %. In some of theseembodiments, the concentration of B₂O₃ in the glass composition may beless than or equal to about 20 mol. %, less than or equal to about 19mol. %, less than or equal to about 18 mol. %, less than or equal toabout 17 mol. %, less than or equal to about 16 mol. %, or less than orequal to about 15 mol. %.

This embodiment of the glass composition used for the antimicrobialarticle 10 may also include at least one alkaline earth oxide. Alkalineearth oxides generally improve the melting behavior of glass by loweringthe temperature required for melting. Moreover, a combination of severaldifferent alkaline earth oxides assists in lowering the liquidustemperature of the glass composition and increasing the liquidusviscosity of the glass composition. The alkaline earth oxides includedin the glass composition are CaO, MgO, SrO and/or combinations thereof.Alkaline earth oxides may be present in the phase-separable glass in aconcentration greater than or equal to about 9 mol. % and less than orequal to about 16 mol. %. In some embodiments, the glass composition maycomprise from about 11 mol. % to about 12 mol. % alkaline earth oxide.The glass composition includes at least CaO as an alkaline earth oxidein a concentration greater than or equal to about 3 mol. % and less thanor equal to about 12 mol. %. The alkaline earth oxide may furtherinclude MgO in a concentration greater than or equal to about 0 mol. %and less than or equal to about 6 mol. %. In some embodiments, theconcentration of MgO in the glass composition may be greater than orequal to about 2 mol. % and less than or equal to about 4 mol. %. Thealkaline earth oxide in the glass composition may also include SrO in aconcentration greater than or equal to about 0 mol. % and less than orequal 6 mol. %. In some embodiments, the SrO may be present in the glasscomposition in a concentration from about 1 mol. % to about 4 mol. %.

In various embodiments, the antimicrobial article 10 and/or the fast andsecond cladding layers 18, 22 may be substantially free from alkalimetals and compounds containing alkali metals. In such embodiments, thearticles and/or cladding layers may contain no more than trace amountsof alkali metals and oxides such as K₂O, Na₂O and Li₂O. However, in someother embodiments, the article 10 and/or first and second claddinglayers 18, 22 may be formed from glass compositions which contain alkaliions. In such embodiments, the presence of the alkali ions mayfacilitate chemically strengthening the glass by ion exchange, therebyimproving the strength of the antimicrobial article 10. Additionally oralternatively, the antimicrobial article 10, and the first and secondcladding layers 18, 22, may contain no more than trace amounts ofphosphorus.

The phase-separable glass may optionally include one or more finingagents. The fining agents may include, for example, SnO₂, As₂O₃, Sb₂O₃and combinations thereof. The fining agents may be present in the glasscomposition in an amount greater than or equal to about 0 mol. % andless than or equal to about 0.5 mol. %. In exemplary embodiments, thefining agent is SnO₂. In these embodiments, SnO₂ may be present in theglass composition in a concentration which is greater than about 0 mol.% and less than or equal to about 0.2 mol. % or even less than or equalto about 0.15 mol. %.

While reference has been made herein to specific phase-separable glasscompositions used for forming the antimicrobial article 10, it should beunderstood that other glass compositions may be used to form theantimicrobial article 10, so long as the glass compositions arephase-separable.

According to one aspect, the antimicrobial article 10 is heat treated toinduce phase-separation in the phase-separable glass, thereby producingthe interconnected matrix 58 of the first phase 50 in which the secondphase 54 is dispersed. The heat treatment process generally includesheating the antimicrobial article 10 to a temperature proximate theupper consulate temperature or spinodal temperature of thephase-separable glass composition which the antimicrobial article 10includes and holding the antimicrobial article 10 at this temperaturefor a time period sufficient to induce the desired amount ofphase-separation in the antimicrobial article 10. In some embodiments,the antimicrobial article 10 is heated to a temperature ranging betweenabout 500° C. to about 1500° C., and more particularly to about 800° C.to about 1200° C. In a specific embodiment, the temperature may be about900° C. The temperature of the heat treatment is selected to heat theantimicrobial article 10 to a range between about 600° C. below thespinodal temperature of the phase-separable glass composition to about100° C. below the spinodal temperature of the phase-separable glasscomposition in order to induce phase-separation in the antimicrobialarticle 10.

The antimicrobial article 10 may be held at the heat treatmenttemperature for a time period sufficient to impart the desired amount ofphase-separation to the antimicrobial article 10. In general, the longerthe antimicrobial article 10 is held at the heat treatment temperature,the greater the amount of phase-separation that occurs in the article10. The antimicrobial article 10 may be held at the heat treatmenttemperature for a time period between about 1 minute and about 10 hours,and more specifically, between about 30 minutes and about 5 hours. In aspecific embodiment, the antimicrobial article 10 is heat treated forabout 2 hours. The size and amount of the second phase 54 may becontrolled by controlling the time and/or temperature of the heattreatment which, in turn, changes properties of the resultantantimicrobial article 10. For example, by controlling the size, quantityand/or dispersion of the regions of the second phase, properties of theantimicrobial article 10 (e.g., index of refraction, light scattering,modulus of elasticity, and/or loss tangent) may be specifically tailoredto meet a desired end use of the article 10.

In some embodiments, the phase-separated glass of the antimicrobialarticle 10 may have a translucent opalescence or opal-type appearancedue to the phase-separation. The opalescence may be desired forapplications in which the antimicrobial article 10 is used to enhancethe aesthetics of an object. In embodiments where the antimicrobialarticle 10 includes at least one metallic constituent which hasprecipitated out, the antimicrobial article 10 may have a color huesimilar to that of the metallic phase (e.g., orange/red for copper,yellow for gold, and white/grey for silver/platinum). In embodimentswhere the antimicrobial article 10 is a laminate structure, thecomposition of the first and second cladding layers 18, 22 and thesubstrate 14 may optionally include a colorant to impart color to theantimicrobial article 10. Exemplary colorants include Fe₂O₃, Cr₂O₃,Co₃O₄, CuO, Au, Ag, NiO, MnO₂, and V₂O₅. In some embodiments,combinations of two or more colorants may be used to achieve a desiredcolor. In other embodiments, colorants may be added to complement acolor hue given to the antimicrobial article 10 by one or more metallicconstituents within the phase-separating glass as explained in greaterdetail below. Additionally or alternatively, the colorants may be addedto the substrate 14 to cooperate with a colorant or metallic constituentof the first and second claddings 18, 22 to provide a desired color tothe antimicrobial article 10.

In embodiments of the antimicrobial article 10 incorporating one or moremetallic constituents, heat treatment of the article 10 may result inthe precipitation of a metallic phase 62 (see FIG. 2) within at leastone of the first and second phases 50, 54, or at interfacestherebetween. The metallic phase 62 may precipitate as at least onediscrete structure within the first and second phases 50, 54, or mayinclude continuous or semi-continuous structures. The metallic phase 62may precipitate in a variety of form factors, including dendrites,cuboid particles, spherical particles, pyramidal particles, and lamellarstructures. In some embodiments, the form factor of the metallic phase62 (e.g., dendrites vs cuboidal structures) may vary with theconcentration of the metallic constituents (e.g., copper) in theantimicrobial article 10. The metallic phase 62 may be precipitated intodiscrete structures having a longest cross sectional length betweenabout 0.01 microns to about 100 microns, about 0.1 microns to about 10microns, and about 0.5 microns to about 2 microns. In a specificembodiment, the structures of the metallic phase 62 may have a longestcross sectional length of about 1 micron. The metallic phase 62 may beprecipitated in a variety of oxidation states, including the “free”state and in ionic states. In embodiments incorporating copper as ametallic constituent, the copper may be precipitated in at least one ofa Cu⁰ and a Cu⁺¹ state. As such, treatments configured to reduce theoxidation state of the metallic phase 62, such as hydrogen treatments,may not be necessary during or after precipitation of the metallic phase62.

Precipitation of certain metallic constituents (e.g., copper, silver,gold, etc.) as the metallic phase 62 in a certain oxidative state (e.g.,Cu⁰ and/or Cu⁺¹) within the less corrosion resistant phase (e.g., thefirst phase 50) may result in an article and/or cladding that exhibitsantimicrobial properties toward at least one type of bacteria, virus, orfungi. In a specific example, the precipitation of the metallic phase 62within the interconnected matrix 58 of the first phase 50 allows theantimicrobial article 10 to exhibit at least a 1 log reduction in aconcentration of at least Staphylococcus aureus, Enterobacter aerogenes,and Pseudomonas aeruginosa bacteria under testing conditions consistentwith the Test Method for Efficacy of Copper Alloy Surfaces as aSanitizer, approved by the U.S. Environmental Protection Agency (“EPACopper Test Protocol”). The EPA Copper Test Protocol is conducted underambient conditions (i.e., at <42% relative humidity, ˜23° C.). Theantimicrobial activity and efficacy of the antimicrobial article 10described herein can be quite high. In some embodiments, theantimicrobial article 10 may have a log kill rate greater than about 1,greater than about 2, greater than about 3, greater than about 4,greater than about 5, and greater than about 6.

Examples

Table 1 lists compositions for various experimental samples. FIGS. 3A-3Cand 4 are scanning electron microscope micrographs generated during abackscattering mode. For all of the samples (e.g., antimicrobialarticles 10) used to generate Table 1 and FIGS. 3A-3C and 4, the sampleswere melted in 1800 cc covered silica crucibles for approximately 14hours at 1650° C., drigaged and remelted for approximately 14 hours at1650° C., then poured. The samples were annealed at 620° C. After theannealing, all samples were heat treated under a nitrogen atmosphere at875° C. for approximately 2 hours. The sample labeled ADN corresponds tothe micrograph of FIG. 3A, the sample labeled ADO corresponds to themicrograph of FIG. 3B, and the sample labeled ADP corresponds to themicrograph of FIG. 3C. In FIG. 4, a bar chart depicts antimicrobialefficacy of the different samples both before and after heat treatmentas well as a copper control sample.

TABLE 1 Chemical composition of articles tested for antimicrobialefficacy. Mole % Melt ID SiO₂ Al₂O₃ B₂O₃ MgO CaO SrO Na₂O SnO₂ ZrO₂ P₂O₅CuO ADM 56.9 1.40 23.30 0 0 0 6.8 0.12 0 0 11.50 ADN 57.51 5.62 18.280.43 4.57 0.44 0.01 0.06 0.04 0 13.04 ADO 55.11 5.38 17.51 0.42 4.380.42 0.01 0.06 0.04 0 16.67 ADP 52.9 5.17 16.82 0.4 4.2 0.4 0.01 0.060.04 0 19.99

Referring to Table 1 and FIGS. 3A-3C, the samples ADN, ADO, and ADPgenerally have an increasing copper concentration. As the copperconcentration in the sample increases, metallic copper (e.g., metallicphase 62) precipitated in the samples during the heat treatment changesfrom a dendritic form (see FIG. 3A) to a cuboid form (See FIG. 3C).Additionally, the metallic copper (e.g., metallic phase 62) transitionsfrom precipitating out only in a boron rich (i.e., less durable or lesscorrosion resistant) phase (e.g., the first phase 50) forming aninterconnected structure (e.g., interconnected matrix 58) and beginsprecipitating in both the boron rich phase and a silicon rich phase(e.g., the second phase 54) with increasing copper concentration.

Referring now to FIG. 4, results of an antimicrobial test on the samples(e.g., embodiments of antimicrobial article 10) as described inconnection with the embodiments of Table 1 under the EPA Copper TestProtocol are depicted. In particular, the EPA antimicrobial efficacytesting was conducted at 23° C. and 42% relative humidity. Notably,samples ADN and ADP demonstrated a log kill value of at least 2 (e.g., a99.00% kill rate) in the pre-heat treat state and all the samplesdemonstrated a log kill value greater than 5 (e.g., 99.999%) after theheat treatment. As a control, log kill data is provided for pure Cumetal samples tested under the same conditions. Consequently, it isevident that antimicrobial articles 10 having precipitated copper phasesprepared according to the disclosure may have antimicrobial efficacy. Itshould be noted that unlike conventional disclosures of copperincorporated into glass substrates, the samples of Table 1 were notreduced (e.g., in a hydrogen atmosphere) to become antimicrobial.However, using a phase-separated glass allows the precipitated copperphase to have an as precipitated oxidation state of at least one of Cu⁰and Cu⁺¹.

Additionally, it appears from the samples that an increase inantimicrobial efficacy is not gained from an increase in theconcentration of copper within the samples. As such, it may beadvantageous, in some embodiments, to limit the copper concentration toabout that of the ADN sample such that peak antimicrobial efficacy isgained using the minimum amount of copper. The precipitation of thecopper phase, as copper concentration increases, takes place within theless durable phase, or less corrosion resistant phase, first. It isbelieved that for metallic copper to impart antimicrobial properties toa phase-separable glass the metallic copper must be precipitated withinthe less durable phase and not the more durable phase (i.e., siliconrich, more corrosion resistant phase). Thus, by utilizing lower copperconcentrations (e.g., comparable to that of the ADN sample, about 8 mol.% to about 12 mol. %) the copper can be precipitated (e.g., metallicphase 62) in only the less durable phase (e.g., first phase 50) therebyboth using less copper and precipitating it in a phase that will impartantimicrobial efficacy to antimicrobial article 10.

While the embodiments disclosed herein have been set forth for thepurpose of illustration, the foregoing description should not be deemedto be a limitation on the scope of the disclosure or the appendedclaims. For example, antimicrobial elements may be incorporated into theantimicrobial article 10 to impart antimicrobial properties and thearticle 10 may be used for medical equipment. Accordingly, variousmodifications, adaptations, and alternatives may occur to one skilled inthe art without departing from the spirit and scope of the presentdisclosure or the appended claims.

What is claimed is:
 1. An article comprising: a phase-separated glass orglass ceramic substrate comprising at least 50 mol. % SiO₂, B₂O₃, andcopper, a first phase, a second phase, and a metallic phase; wherein,the first phase is an interconnected matrix and comprises a greater molepercentage of B₂O₃ than the second phase; wherein, the second phase isdiscontinuous, dispersed within the interconnected matrix of the firstphase, and comprises a greater mole percentage of SiO₂ than the firstphase; and wherein, the metallic phase is disposed predominately in thesecond phase, and the metallic phase comprises copper in at least one ofa Cu⁰ and a Cu⁺¹ state.
 2. The article of claim 1, wherein the articleexhibits an antimicrobial efficacy log reduction of 3 or greater (i.e.,at least 99.9%).
 3. The article of claim 1, wherein the antimicrobialefficacy log reduction that the article exhibits is 5 or greater (i.e.,at least 99.999%).
 4. The article of claim 1, wherein the metallic phaseis disposed in both the first phase and the second phase.
 5. The articleof claim 4, wherein at least a portion of the metallic phase dispersedin the first phase is in a dendritic form; and at least a portion of themetallic phase dispersed in the second phase is in a cuboid form.
 6. Thearticle of claim 1, wherein at least a portion of the metallic phase isin a cuboid form.
 7. The article of claim 1, wherein the metallic phasecomprises discrete structures having a longest cross-sectional length of0.1 microns to 10 microns.
 8. The article of claim 1, wherein thesubstrate comprises: 50 mol % to 70 mol % SiO₂; Al₂O₃, wherein the Al₂O₃is 10 mol. % or less; 14 mol % to 25 mol % B₂O₃; 11.50 mol % to 19.99mol % CuO; and no more than trace amounts of phosphorous.
 9. The articleof claim 1 further comprising another substrate bonded to the substrate,thus forming a laminate structure.
 10. The article of claim 1, whereinthe substrate further comprises a colorant selected from the groupconsisting of Fe₂O₃, Cr₂O₃, Co₃O₄, CuO, Au, Ag, NiO, MnO₂, and V₂O₅. 11.An article comprising: a phase-separated glass or glass ceramicsubstrate comprising at least 50 mol. % SiO₂, B₂O₃, and copper, a firstphase, a second phase, and a metallic phase; wherein, the first phase isan interconnected matrix and comprises a greater mole percentage of B₂O₃than the second phase; wherein, the second phase is discontinuous,dispersed within the interconnected matrix of the first phase, andcomprises a greater mole percentage of SiO₂ than the first phase; andwherein, the metallic phase is disposed in predominantly the firstphase, and the metallic phase comprises copper in at least one of a Cu⁰and a Cu⁺¹ state.
 12. The article of claim 11, wherein the articleexhibits an antimicrobial efficacy log reduction of 3 or greater (i.e.,at least 99.9%).
 13. The article of claim 11, wherein the antimicrobialefficacy log reduction that the article exhibits is 5 or greater (i.e.,at least 99.999%).
 14. The article of claim 11, wherein the metallicphase is disposed in both the first phase and the second phase; andwherein the metallic phase disposed in the second phase comprisesdiscrete structures having a longest cross-sectional length of 0.1microns to 10 microns.
 15. The article of claim 11, wherein at least aportion of the metallic phase is in a dendritic form.
 16. The article ofclaim 11, wherein the substrate comprises: 50 mol % to 70 mol % SiO₂;Al₂O₃, wherein the Al₂O₃ is 10 mol. % or less; 14 mol % 25 mol % B₂O₃;11.50 mol % to 19.99 mol % CuO, no more than trace amounts ofphosphorous; and a colorant selected from the group consisting of Fe₂O₃,Cr₂O₃, Co₃O₄, Au, Ag, NiO, MnO₂, and V₂O₅.
 17. The article of claim 11further comprising another substrate bonded to the substrate, thusforming a laminate structure.
 18. The article of claim 11, wherein thesecond phase comprises less than 1.0 mol % copper.
 19. The article ofclaim 11, wherein the second phase comprises less than 0.5 mol % copper.20. A method of creating an antimicrobial glass article, comprising thesteps: providing a phase-separable glass article having a bulk copperconcentration between about 1.0 mol. % and about 20 mol. %; heattreating the article to form an interconnected matrix having at leastone second phase disposed throughout the matrix; and precipitating acopper phase within the matrix and apart from the second phase, whereinthe second phase comprises a copper concentration of less than about 1.0mol. %.